'use strict';

const autoprefixer = require('autoprefixer');
const path = require('path');
const webpack = require('webpack');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const ExtractTextPlugin = require('extract-text-webpack-plugin');
const ManifestPlugin = require('webpack-manifest-plugin');
const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
const SWPrecacheWebpackPlugin = require('sw-precache-webpack-plugin');
const eslintFormatter = require('react-dev-utils/eslintFormatter');
const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
const paths = require('./paths');
const getClientEnvironment = require('./env');

// Webpack uses `publicPath` to determine where the app is being served from.
// It requires a trailing slash, or the file assets will get an incorrect path.
const publicPath = paths.servedPath;
// Some apps do not use client-side routing with pushState.
// For these, "homepage" can be set to "." to enable relative asset paths.
const shouldUseRelativeAssetPaths = publicPath === './';
// Source maps are resource heavy and can cause out of memory issue for large source files.
const shouldUseSourceMap = process.env.GENERATE_SOURCEMAP !== 'false';
// `publicUrl` is just like `publicPath`, but we will provide it to our app
// as %PUBLIC_URL% in `index.html` and `process.env.PUBLIC_URL` in JavaScript.
// Omit trailing slash as %PUBLIC_URL%/xyz looks better than %PUBLIC_URL%xyz.
const publicUrl = publicPath.slice(0, -1);
// Get environment variables to inject into our app.
const env = getClientEnvironment(publicUrl);

// Assert this just to be safe.
// Development builds of React are slow and not intended for production.
if (env.stringified['process.env'].NODE_ENV !== '"production"') {
      throw new Error('Production builds must have NODE_ENV=production.');
}

// Note: defined here because it will be used more than once.
const cssFilename = 'static/css/[name].[contenthash:8].css';

// ExtractTextPlugin expects the build output to be flat.
// (See https://github.com/webpack-contrib/extract-text-webpack-plugin/issues/27)
// However, our output is structured with css, js and media folders.
// To have this structure working with relative paths, we have to use custom options.
const extractTextPluginOptions = shouldUseRelativeAssetPaths
      ? // Making sure that the publicPath goes back to to build folder.
      { publicPath: Array(cssFilename.split('/').length).join('../') }
      : {};

// This is the production configuration.
// It compiles slowly and is focused on producing a fast and minimal bundle.
// The development configuration is different and lives in a separate file.
module.exports = {
      // Don't attempt to continue if there are any errors.
      bail: true,
      // We generate sourcemaps in production. This is slow but gives good results.
      // You can exclude the *.map files from the build during deployment.
      devtool: shouldUseSourceMap ? 'source-map' : false,
      // In production, we only want to load the polyfills and the app code.
      entry: [require.resolve('./polyfills'), paths.appIndexJs],
      output: {
            // The build folder.
            path: paths.appBuild,
            // Generated JS file names (with nested folders).
            // There will be one main bundle, and one file per asynchronous chunk.
            // We don't currently advertise code splitting but Webpack supports it.
            filename: 'static/js/[name].[chunkhash:8].js',
            chunkFilename: 'static/js/[name].[chunkhash:8].chunk.js',
            // We inferred the "public path" (such as / or /my-project) from homepage.
            publicPath: publicPath,
            // Point sourcemap entries to original disk location (format as URL on Windows)
            devtoolModuleFilenameTemplate: info =>
                  path
                        .relative(paths.appSrc, info.absoluteResourcePath)
                        .replace(/\\/g, '/'),
      },
      resolve: {
            // This allows you to set a fallback for where Webpack should look for modules.
            // We placed these paths second because we want `node_modules` to "win"
            // if there are any conflicts. This matches Node resolution mechanism.
            // https://github.com/facebookincubator/create-react-app/issues/253
            modules: ['node_modules', paths.appNodeModules].concat(
                  // It is guaranteed to exist because we tweak it in `env.js`
                  process.env.NODE_PATH.split(path.delimiter).filter(Boolean)
            ),
            // These are the reasonable defaults supported by the Node ecosystem.
            // We also include JSX as a common component filename extension to support
            // some tools, although we do not recommend using it, see:
            // https://github.com/facebookincubator/create-react-app/issues/290
            // `web` extension prefixes have been added for better support
            // for React Native Web.
            extensions: ['.web.js', '.mjs', '.js', '.json', '.web.jsx', '.jsx'],
            alias: {

                  // Support React Native Web
                  // https://www.smashingmagazine.com/2016/08/a-glimpse-into-the-future-with-react-native-for-web/
                  'react-native': 'react-native-web',
            },
            plugins: [
                  // Prevents users from importing files from outside of src/ (or node_modules/).
                  // This often causes confusion because we only process files within src/ with babel.
                  // To fix this, we prevent you from importing files out of src/ -- if you'd like to,
                  // please link the files into your node_modules/ and let module-resolution kick in.
                  // Make sure your source files are compiled, as they will not be processed in any way.
                  new ModuleScopePlugin(paths.appSrc, [paths.appPackageJson]),
            ],
      },
      module: {
            strictExportPresence: true,
            rules: [
                  // TODO: Disable require.ensure as it's not a standard language feature.
                  // We are waiting for https://github.com/facebookincubator/create-react-app/issues/2176.
                  // { parser: { requireEnsure: false } },

                  // First, run the linter.
                  // It's important to do this before Babel processes the JS.
                  {
                        test: /\.(js|jsx|mjs)$/,
                        enforce: 'pre',
                        use: [
                              {
                                    options: {
                                          formatter: eslintFormatter,
                                          eslintPath: require.resolve('eslint'),

                                    },
                                    loader: require.resolve('eslint-loader'),
                              },
                        ],
                        include: paths.appSrc,
                  },
                  {
                        // "oneOf" will traverse all following loaders until one will
                        // match the requirements. When no loader matches it will fall
                        // back to the "file" loader at the end of the loader list.
                        oneOf: [
                              // "url" loader works just like "file" loader but it also embeds
                              // assets smaller than specified size as data URLs to avoid requests.
                              {
                                    test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
                                    loader: require.resolve('url-loader'),
                                    options: {
                                          limit: 10000,
                                          name: 'static/media/[name].[hash:8].[ext]',
                                    },
                              },
                              // Process JS with Babel.
                              {
                                    test: /\.(js|jsx|mjs)$/,
                                    include: paths.appSrc,
                                    loader: require.resolve('babel-loader'),
                                    options: {

                                          compact: true,
                                    },
                              },
                              // The notation here is somewhat confusing.
                              // "postcss" loader applies autoprefixer to our CSS.
                              // "css" loader resolves paths in CSS and adds assets as dependencies.
                              // "style" loader normally turns CSS into JS modules injecting <style>,
                              // but unlike in development configuration, we do something different.
                              // `ExtractTextPlugin` first applies the "postcss" and "css" loaders
                              // (second argument), then grabs the result CSS and puts it into a
                              // separate file in our build process. This way we actually ship
                              // a single CSS file in production instead of JS code injecting <style>
                              // tags. If you use code splitting, however, any async bundles will still
                              // use the "style" loader inside the async code so CSS from them won't be
                              // in the main CSS file.
                              {
                                    test: /\.css$/,
                                    loader: ExtractTextPlugin.extract(
                                          Object.assign(
                                                {
                                                      fallback: {
                                                            loader: require.resolve('style-loader'),
                                                            options: {
                                                                  hmr: false,
                                                            },
                                                      },
                                                      use: [
                                                            {
                                                                  loader: require.resolve('css-loader'),
                                                                  options: {
                                                                        importLoaders: 1,
                                                                        minimize: true,
                                                                        sourceMap: shouldUseSourceMap,
                                                                  },
                                                            },
                                                            {
                                                                  loader: require.resolve('postcss-loader'),
                                                                  options: {
                                                                        // Necessary for external CSS imports to work
                                                                        // https://github.com/facebookincubator/create-react-app/issues/2677
                                                                        ident: 'postcss',
                                                                        plugins: () => [
                                                                              require('postcss-flexbugs-fixes'),
                                                                              autoprefixer({
                                                                                    browsers: [
                                                                                          '>1%',
                                                                                          'last 4 versions',
                                                                                          'Firefox ESR',
                                                                                          'not ie < 9', // React doesn't support IE8 anyway
                                                                                    ],
                                                                                    flexbox: 'no-2009',
                                                                              }),
                                                                        ],
                                                                  },
                                                            },
                                                      ],
                                                },
                                                extractTextPluginOptions
                                          )
                                    ),
                                    // Note: this won't work without `new ExtractTextPlugin()` in `plugins`.
                              },
                              // "file" loader makes sure assets end up in the `build` folder.
                              // When you `import` an asset, you get its filename.
                              // This loader doesn't use a "test" so it will catch all modules
                              // that fall through the other loaders.
                              {
                                    loader: require.resolve('file-loader'),
                                    // Exclude `js` files to keep "css" loader working as it injects
                                    // it's runtime that would otherwise processed through "file" loader.
                                    // Also exclude `html` and `json` extensions so they get processed
                                    // by webpacks internal loaders.
                                    exclude: [/\.(js|jsx|mjs)$/, /\.html$/, /\.json$/, /\.scss$/],
                                    options: {
                                          name: 'static/media/[name].[hash:8].[ext]',
                                    },
                              },
                              {
                                    test: /\.scss$/,
                                    loaders: ['style-loader', 'css-loader', 'sass-loader'],
                              },

                              // ** STOP ** Are you adding a new loader?
                              // Make sure to add the new loader(s) before the "file" loader.
                        ],
                  },
            ],
      },
      plugins: [
            // Makes some environment variables available in index.html.
            // The public URL is available as %PUBLIC_URL% in index.html, e.g.:
            // <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">
            // In production, it will be an empty string unless you specify "homepage"
            // in `package.json`, in which case it will be the pathname of that URL.
            new InterpolateHtmlPlugin(env.raw),
            // Generates an `index.html` file with the <script> injected.
            new HtmlWebpackPlugin({
                  inject: true,
                  template: paths.appHtml,
                  minify: {
                        removeComments: true,
                        collapseWhitespace: true,
                        removeRedundantAttributes: true,
                        useShortDoctype: true,
                        removeEmptyAttributes: true,
                        removeStyleLinkTypeAttributes: true,
                        keepClosingSlash: true,
                        minifyJS: true,
                        minifyCSS: true,
                        minifyURLs: true,
                  },
            }),
            // Makes some environment variables available to the JS code, for example:
            // if (process.env.NODE_ENV === 'production') { ... }. See `./env.js`.
            // It is absolutely essential that NODE_ENV was set to production here.
            // Otherwise React will be compiled in the very slow development mode.
            new webpack.DefinePlugin(env.stringified),
            // Minify the code.
            new webpack.optimize.UglifyJsPlugin({
                  compress: {
                        warnings: false,
                        // Disabled because of an issue with Uglify breaking seemingly valid code:
                        // https://github.com/facebookincubator/create-react-app/issues/2376
                        // Pending further investigation:
                        // https://github.com/mishoo/UglifyJS2/issues/2011
                        comparisons: false,
                  },
                  mangle: {
                        safari10: true,
                  },
                  output: {
                        comments: false,
                        // Turned on because emoji and regex is not minified properly using default
                        // https://github.com/facebookincubator/create-react-app/issues/2488
                        ascii_only: true,
                  },
                  sourceMap: shouldUseSourceMap,
            }),
            // Note: this won't work without ExtractTextPlugin.extract(..) in `loaders`.
            new ExtractTextPlugin({
                  filename: cssFilename,
            }),
            // Generate a manifest file which contains a mapping of all asset filenames
            // to their corresponding output file so that tools can pick it up without
            // having to parse `index.html`.
            new ManifestPlugin({
                  fileName: 'asset-manifest.json',
            }),
            // Generate a service worker script that will precache, and keep up to date,
            // the HTML & assets that are part of the Webpack build.
            new SWPrecacheWebpackPlugin({
                  // By default, a cache-busting query parameter is appended to requests
                  // used to populate the caches, to ensure the responses are fresh.
                  // If a URL is already hashed by Webpack, then there is no concern
                  // about it being stale, and the cache-busting can be skipped.
                  dontCacheBustUrlsMatching: /\.\w{8}\./,
                  filename: 'service-worker.js',
                  logger(message) {
                        if (message.indexOf('Total precache size is') === 0) {
                              // This message occurs for every build and is a bit too noisy.
                              return;
                        }
                        if (message.indexOf('Skipping static resource') === 0) {
                              // This message obscures real errors so we ignore it.
                              // https://github.com/facebookincubator/create-react-app/issues/2612
                              return;
                        }
                        console.log(message);
                  },
                  minify: true,
                  // For unknown URLs, fallback to the index page
                  navigateFallback: publicUrl + '/index.html',
                  // Ignores URLs starting from /__ (useful for Firebase):
                  // https://github.com/facebookincubator/create-react-app/issues/2237#issuecomment-302693219
                  navigateFallbackWhitelist: [/^(?!\/__).*/],
                  // Don't precache sourcemaps (they're large) and build asset manifest:
                  staticFileGlobsIgnorePatterns: [/\.map$/, /asset-manifest\.json$/],
            }),
            // Moment.js is an extremely popular library that bundles large locale files
            // by default due to how Webpack interprets its code. This is a practical
            // solution that requires the user to opt into importing specific locales.
            // https://github.com/jmblog/how-to-optimize-momentjs-with-webpack
            // You can remove this if you don't use Moment.js:
            new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/),
      ],
      // Some libraries import Node modules but don't use them in the browser.
      // Tell Webpack to provide empty mocks for them so importing them works.
      node: {
            dgram: 'empty',
            fs: 'empty',
            net: 'empty',
            tls: 'empty',
            child_process: 'empty',
      },
};
